Important notice! Pokemon Croagunk is a fictional character of humans.There is only single Creator of everything and anythingAll Pokemon are made up by humans based on real animals or existing objects.The stroies of Pokemon are all fictional and in most cases illogical or nonsense.Games are for only fun time and do never put any spiritual/religional or deity meaning into them!Never pass your necessary jobs and duties due to gameplaying!

Official Pokemon Info from Bulbapedia (Content is available under Attribution-NonCommercial-ShareAlike 2.5)

Biology

Croagunk is a dark blue, bipedal Pokémon that resembles a poison dart frog. It has yellow eyes, which are surrounded by black markings. There are orange, expandable pouches on its cheeks, and its teeth are wide and flat. A black marking encircles its upper arms and chest, and there are white bands around its chest. The white markings are slightly higher up on the female Croagunk than the male. It has three fingers and toes, most of which are black. The only digits that are not black are its center fingers, which are orange instead.

Croagunk's cheek pouches and fingers contain a poisonous fluid. However, the fluid squeezed from its finger is also a significant ingredient in remedies for lower back pain. The cheek pouches can be used to make an unnerving sound. When its opponents are distracted, it tries to stab them with its fingers. Despite this, it is a mild Pokémon, fighting only to ensure its own survival.

Croagunk and its evolution are also the only Pokémon with a double weakness to the Psychic type, due to their unique typing.

Croagunk is one of few Pokémon to have its handheld game sprite differ from its 3-D image. While in Pokémon Diamond, Pearl, and Platinum it is shown to have pink cheeks, its 3-D models, official artwork, and anime appearance show it with yellow-orange cheeks.

In Platinum, in front of the PastoriaGreat Marsh, if the player stands behind the Croagunk Wall, with their head sticking out of it, a wild Croagunk may come by, cry out, and then walk to the Great Marsh.

In the Pastoria City Poké Mart, a wooden Croagunk statue can be seen on the counter. If interacted with, it will mention how "Even though it's made of wood, it still seems like it's seeping poison..."